The present invention relates to reclosable packaging and, in particular to an improved zipper for use in the manufacture of such packaging.
Reclosable plastic bags are growing increasingly popular both for storage purposes and as primary packaging for food stuffs and other products. Such bags are formed with plastic zipper having profiles with mating interengageable elements. A problem that has been encountered with such zippers is that when the user opens the zipper, if too much force is exerted a run may develop down one or both side seams of the bag. To avoid this from happening, it has heretofore been proposed to crimp or crush the ends of the zipper. While such crimping works fine for sliderless packages, the result is not always satisfactory when a slider is provided to facilitate opening and closing the zipper elements. In such case, the slider may be pulled over the crimp and off the package if too much force is exerted.
In order to maintain the slider on the zipper profiles, it has heretofore been suggested to provide stops at the ends of the zipper. The prior art is replete with suggestions as to how the end stops may be formed. Thus, in U.S. Pat. No. 5,131,121 end stops are formed of the material at the ends of the zipper by deforming the material to extend outwardly from the sides of the bag. In U.S. Pat. Nos. 5,161,286, 5,448,807 and U.S. Pat. No. 5,833,791 a clip is provided at the ends of the zipper.